3 Reasons Interior French Drains Are Not A Good Waterproofing Option

A classic french drain is a trench dug into the ground, to direct groundwater away from (or to) a specific area.  It’s usually lined with gravel or rock, with a perforated pipe placed in the center.  If your yard becomes a pond every time it rains, a french drain is an excellent way to make this water collect somewhere else (like a drainage ditch).  

Acculevel is a family-owned and operated company that specializes in foundation repair and waterproofing.  Since Andy Beery started the company in 1996, we’ve helped restore health and stability to more than 30,000 homes throughout our service area.  

We offer several different waterproofing options, to meet the needs of homes and their varying  structures.  And we offer the best warranties in our industry.  With the exception of baseboard drainage, we guarantee that our waterproofing systems will not clog or fail for the life of your structure.  In order to keep that promise, our water drainage systems have to be the best products available, and they must be installed expertly by professionals.

We do not install french drains, because we are primarily focused on interior drainage.  And we do not install french drains inside homes, because they do not meet our particular standards.  In this article, we’re going to share the three primary reasons we don’t recommend interior french drains. 

 

Encourages Shearing

To install any type of water drainage system in a basement, you have to break up the perimeter of the concrete floor.  The drainage is installed below the floor either on top of (or next to) the foundation’s footer.  

French Drain Method

French drains are not normally covered back up with concrete; they’re either left entirely uncovered, or covered with a removable grate.  This is done so that when it clogs, it’s easier to access the system and clean it out. 

However, the concrete that was removed from the perimeter?  It had an important structural purpose.  It’s what connected the walls to the floor, adding structural stability to the walls.  It also helped prevent the wall from shearing.  Foundation shearing is an industry term for how a foundation wall moves, when it’s under tremendous stress from hydrostatic pressure.   

graphic of shearing wallThis iIllustration was done by the author, who is not a graphic designer. 

You can see from the graphic that shearing normally would only occur at the second row of blocks (or higher).  This is because the floor is supposed to hold the first row in place.  But if there’s missing concrete, shearing can happen farther down, causing more significant damage. 

 

Our Waterproofing Method

We also break up the perimeter of the floor, to allow for water drainage to be installed.  If the basement walls are concrete block, we normally drill weep holes in the bottom block to drain out any water accumulating through the wall.  

This illustration was also done by the author.

After the weep holes are drilled, we cover the bottom row of blocks with a dimple board.  This board ensures that water coming out of the holes is funneled directly into the drainage system, without getting on your floor.  The dimpling is staggered, so that it allows the water to move down the channels, while also helping to reinforce the wall.  

close up of drainage and dimple boardThis photo was taken by an Acculevel crew member after installing water drainage.  

In the photo above, you can see the dimple board covering the weep holes.  You can also clearly see that we do not leave any gap or opening above the drainage system.  We pour new concrete over the installed system, because we are confident it will not need to be dug up or opened.  

 

Exposed Drains Don’t Reduce Moisture

French drains are left open or exposed, so they can be easily accessed for clean-up.  This makes sense from a drainage perspective.  But it won’t reduce the humidity in your home, because the water is still exposed to the air in your basement or crawl space.  

If your only goal is to stop water from collecting on your basement floor, this would be okay.  But most homeowners want to accomplish more.  At Acculevel, we expect our waterproofing to:

  • manage water intrusion.
  • help prevent biological growth (like mold and mildew).
  • preserve the strength and stability of your wooden flooring (beams, joists, etc). 
  • Improve your air quality.

We often recommend adding a whole-house dehumidifier to further these goals, especially if you are experiencing significant water entry.

 

French Drains Can and Will Clog

A french drain uses a perforated pipe to filter and collect water.  Water flows into your basement through the wall, from the join between wall and floor, then moves over to the french drain trench.  Some water may come up from under the floor, seeping into the gravel and then making its way into the pipe.

All of this water brings silt, soil, and other debris with it.  Anything that the gravel doesn’t filter out will get into the drainage.  Over time, this builds up and clogs the system.  That’s why the system is open- so you can find and remove these clogs.  

A waterproofing drainage system from Acculevel goes under the floor, and is permanently covered with concrete.  Water that seeps in through the wall or from the join between wall and floor is blocked by the dimple board.  It’s routed by the dimple board directly into the water drainage- without getting your actual basement wet.  

Our under-floor drainage systems are designed to either fit on or next to the concrete footer that supports your foundation walls.  These systems filter out clogging materials, so that there is no need to clean them out.  (With one exception: if you have iron ore bacteria in your water, we will install cleaning ports before we pour new concrete.)

We guarantee our water drainage systems will not clog or fail for the life of your structure.  

 

What Should You Do Next?

Do you want to learn more about waterproofing, hydrostatic pressure, and the benefits of a dehumidifier?  Check out our Basement Waterproofing Guide, a free and in-depth review of everything homeowners need to know about waterproofing. 

link to our waterproofing guide

If you have water in your basement, and would like more information about the best water drainage system for your home, contact Acculevel at 866-669-3349 or by requesting an estimate.  We will make an appointment for you to meet with one of our trusted and experienced project managers.  

They will listen to your concerns, inspect your home, and clearly explain what options are available.  Our goal is to provide you with a whole-home solution designed to meet your needs.   We believe everyone deserves a safe and healthy home, and we understand that your home is the single largest investment you have. 

If you don’t live in our service area, please make sure you are working with an accredited and insured member of the Better Business Bureau.  If you’re not sure where to start, we recommend asking neighbors, your local HOA, or the realtor you worked with on your home.  All of these are good sources for finding someone reputable and trustworthy.  You can also use our guide of questions to ask a contractor, to make sure that you find the right contractor for you. 

 

Kelly Kater

Over her twenty year career, Kelly has worked in a wide variety of fields: secondary education, nursing, biology, elder care, the postal service, multicultural development, and academia. She has developed a skill for translating industry-specific jargon into everyday language. Her goal is to share the knowledge and experience of the Acculevel team with homeowners, in a way that is both engaging and informative.

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